Abstract

Bone fractures at the end of lay are a significant problem in egg-laying strains of
hens. The objective of the current study was to identify quantitative trait loci (QTL)
associated with bone mineralization and strength in a chicken resource population.
Layer (White Leghorn hens) and broiler (Cobb-Cobb roosters) lines were crossed to
generate an F2 population of 508Â hens over seven hatches, and 26 traits related to
bone integrity, including bone mineral density (BMD) and content (BMC), were measured.
Genotypes of 120 microsatellite markers on 28 autosomal groups were determined, and
interval mapping was conducted to identify QTL regions. Twenty-three tests representing
three chromosomal regions (chromosomes 4, 10 and 27) contained significant QTL that
surpassed the 5% genome-wise threshold, and 47 tests representing 15 chromosomes identified
suggestive QTL that surpassed the 5% chromosome-wise threshold. Although no significant
QTL influencing BMD and BMC were detected after adjusting for variation in body weight
and egg production, multiple suggestive QTL were found. These results support previous
experiments demonstrating an important genetic regulation of bone strength in chickens,
but suggest the regulation may be due to the effects of multiple genes that each account
for relatively small amounts of variation in bone strength.